IRH1–the first aromatic hybrid rice in Iran

Abstract

Increasing rice production in Iran, a country with limited land and water resources, is a challenging task, especially with consumer demand largely favoring varieties with superior grain quality. In 2000, Iran imported 1.2 million t of rice. But, in recent years, with increased adoption of improved varieties and with favorable climatic conditions, importation has been reduced to 0.98 million t (FAO 2006). However, with recent fluctuations in the availability of surplus rice from rice-exporting countries and the increasing rice demand in Asia alone, Iran has to initiate a well-drawn plan to attain self-sufficiency and sustain its rice production in the long term. Among the available approaches, the most viable is to pursue hybrid rice technology for Iran, on the basis of success achieved in India, Vietnam, and the Philippines. Hybrid rice technology could easily deliver hybrids with medium quality in the short term, with a 1.5−2.0 t ha–1 advantage over improved check varieties (such as Khazar), while superior quality with high yield can be combined in the hybrids, provided a systematic approach is followed. A comparative yield trial in 2002 involving four promising hybrids and their parents and inbred check variety Khazar revealed exceptional performance of the hybrid combination IR58025A/IR42686R. This hybrid gave the highest standard heterosis (57.9%), heterobeltiosis (53.3%), and commercial heterosis (45.2%) over improved check variety Khazar (Table 1). Furthermore, the number of days to 50% flowering of the parents differed by only 3, with the R line flowering earlier and having a relatively better quality than Khazar (data not shown). A pooled analysis of variance for the adaptive yield trial conducted over two different sites for 2003-04 showed significant yield differences among genotypes and in site-by-genotype-by-year interaction. IR58025A/IR42686R gave an average yield of 9.2 t ha–1 with a yield advantage of 28% over Khazar (Table 1). It was named IRH1. On-farm trials conducted in 2005 at four locations gave an impressive yield of 12 t ha–1, which was 85% higher than Khazar’s 6.5 t ha–1 (Table 2). The hybrids planning breeding programs to control genetic erosion and vulnerability, which is a great possibility because of the observed genetic uniformity. Reshuffling the genetic constituents is also necessary to increase yield potential. References Delannax X, Todgers DM, Palmer RG. 1983. Relative genetic contribution among ancestral lines to North American soybean cultivars. Crop Sci. 23:944-949. Dilday RH. 1990. Contribution of ancestral lines in the development of new cultivars of rice. Crop Sci. 30:905-911. Martin JM, Balke TK, Hockett EA. 1991. Diversity among North American spring barley cultivars based on coefficients of parentage. Crop Sci. 31:1131-1137. St. Martin SK. 1982. Effective population size for the soybean improvement program in maturity groups 00 to IV. Crop Sci. 22:151152.